Add ability to select multiple party sizes to filter in matches page

[evilmtv]

Is your feature request related to a problem? Please describe.
Unable to select party games using the Party Size filter in matches page.

Describe the solution you'd like
Ability to select multiple party sizes rather than being limited to one.

Describe alternatives you've considered
Simply solo vs party may be simpler but I can see users needing to select specific party sizes.

Teachability, Documentation, Adoption, Migration Strategy
Simply make all party size options selectable and a Apply button at the bottom

[howardchung]

Adding a solo/party option would be probably be simplest, it could be added just as an additional filter on the backend. We could remove the individual party size selector on the UI to avoid confusion

[Argn0]

Or just have both options like Dotabuff.